The Trump administration has approved the sale by private companies of sniper rifles, scopes and ammunition to Ukraine but held off on a larger weapons package backed by Defense Secretary Jim Mattis to counter Russia.

At the Pentagon on Thursday, Deputy Defense Secretary Patrick Shanahan told reporters that any decisions on the sale of anti-tank and anti-aircraft weapons repeatedly requested by the Kiev government would come from the State Department.

"Those types of decisions come from the State Department" on foreign military sales, he said.

"We're standing by waiting for the State Department" to sign off on additional weaponry for Ukraine, Shanahan said, but noted that increases in foreign military sales to allies are a major policy focus for Mattis.

For years, the U.S. has debated whether to provide Ukraine with "lethal" defensive weapons to counter separatists backed by Russia in eastern Ukraine.

The small-arms sale was announced Wednesday, a day after U.S. and Western observers reported an escalation of fighting along cease-fire lines in eastern Ukraine.

In a speech in Washington earlier this week, Kurt Volker, the administration's special envoy for Ukraine, said that shelling Tuesday resulted in "one of the most violent nights" of the war, which began in Spring 2014.

"A lot of people think that this has somehow turned into a sleepy, frozen conflict and it's stable," he said, calling that view of the situation in eastern Ukraine "completely wrong."

At the State Department, spokeswoman Heather Nauert made the technical distinction that the small-arms sale is between Ukraine and private companies -- the U.S. only approved the export licenses.

"The U.S. government is not selling the Ukrainian government these weapons," Nauert said. "Under the previous two administrations, the U.S. government has approved export licenses to Ukraine, so this is nothing new."

However, the small-arms sale could be seen as testing the waters for a $47 million package including Javelin anti-tank missiles that has the backing of Mattis and Army Lt. Gen. H.R. McMaster, the White House national security adviser.

In a statement Wednesday night, Sen. John McCain, R-Arizona, chairman of the Senate Armed Services Committee, said, "The sale of sniper rifles and ammunition must only be a first step."

The senator, who is battling the aftereffects of chemotherapy for cancer, added, "I urge the president to authorize additional sales of defensive lethal weapons, including anti-tank munitions, and to fully utilize security assistance funds provided by the Congress to enable Ukraine to defend its sovereignty and territorial integrity."